Stand beside a low step.
Place the ball of your inside foot on the step.
The toes of your foot should be slightly further back than the heel of your foot on the floor.
When ready, move your weight over to your bent leg and step up pushing through the ball of your foot.
Straighten your knee and let your heel lower against the step.
Next, push up onto your tiptoes and then bend your knee.
Return to the start position, and repeat.